The overall aim of this project is to determine whether human cytomegalovirus (HCMV) contributes to the pathogenesis of acquired immune deficiency syndrome (AIDS) by interacting specifically with the AIDS virus (HIV). AIDS is a disease which has reached epidemic numbers with greater than 40,000 new cases worldwide predicted over the next two years. Individuals with this syndrome develop severe immunosuppression accompanied by opportunistic infections, most commonly HCMV. Although the precise pathogenic mechanism or this syndrome has not been identified, the etiological agent of AIDS is the human immunodeficiency virus (HIV). HCMV possesses many similarities to the AIDS virus including suppression of the immune system, spread by venereal transmission and blood transfusion, and infection of OKT4 lymphocytes and monocytes. The ability of HCMV to transactivate HIV and our recent co-localization of both viruses in single cells in tissue with aberrant HCMV growth suggests a symbiotic relationship. Therefore, the focus of this project will be to determine the in vivo and in vitro interactions between HCMV and HIV which may contribute to the pathogenesis of AIDS. We will first identify the tissues and cell types from AIDS patients infected by HIV and HCMV using in situ hybridization and immunocytochemistry concentrating on brain, rectal tissue, lymph node, spleen, and peripheral blood. We will determine the extent of HCMV expression within these tissues and using double-labeling techniques assess the frequency of HIV and HCMV coinfection of single cells. We will also examine the ability of the HIV to transactivate HCMV immediate-early (IE), (E), and late (L) genes normally quiescent in lymphocyte cells in culture, peripheral blood mononuclear (PBMN) cells, PBMN subset populations, and endothelial cells. Specific HCMV genes representing the three kinetic classes will be examined in these cells coinfected with the AIDS virus by northern analysis and in vitro nuclear runoff transcription of nuclei. We will finally examine the ability of the AIDS virus to directly activate HCMV IE, E, and L promoters in transient transfection assays. Comparison of these in vivo and in vitro results will give an insight into the pathogenesis of the disease.